I've tried a variety of cable clips/hooks. Those with adhesive (they eventually fall off. Not sure why, but there must be something about the plywood I use) then I discovered these. Solved my problem. Easy to install, anywhere with just a drill and they open/close easily. If I were starting anew, this would be my choice.
From Amazon: GEZIDEA Light Hanger Hooks, Ceiling Hooks,Screw-in Hooks for Hanging String Lights and Wire,Plants,Wind Chimes,White,20 Pack (Search "Light hangar clips" and you'll get a variety)